Flexible plastic bags are widely used for a variety of purposes such as storing food items, either temporarily as in the case of packaging snacks or long term as in the case of freezer storage. Plastic bags of this style typically include flexible sidewalls made from, for example, polyethylene, that define an opening and an internal volume accessible through the opening. To seal the bag, interlocking closure strips may be provided about the rim of the opening.
One common problem which occurs with such bags is that, after the opening has been sealed, latent air may remain trapped in the internal volume. In addition to undesirably increasing the overall size of the sealed bag, the trapped air can cause spoilation of food items stored in the internal volume. Therefore, a one-way valve element may be attached to a flexible sidewall and communicating with the internal volume. The one-way valve element allows for the evacuation of the trapped air from the internal volume while also preventing the ingress of air from the surrounding environment into the internal volume. The one-way valve element may be activated in various ways such as, for example, by applying compressive pressure to the flexible sidewalls to force air from the internal volume or by engaging a nozzle of a vacuum source to the one-way valve element to draw air from the internal volume. An example of a one-way valve element that operates in conjunction with a vacuum source is provided in U.S. Pat. No. 6,581,641.
A problem that may arise with such bags that include one-way valve elements is that, during evacuation, the flexible sidewall may collapse against itself, against the contents of the bag, or against the valve element thereby preventing air from accessing the valve element. Another problem is that contents of the stored food items may contain fluids or juices that, during evacuation, may be drawn into and thereby contaminate the valve element. As will be appreciated, the contaminated valve element may result in sanitary issues and may not function properly. These and other problems are remedied by the invention described herein.